Fescue grasses (Festuca species) are widely used as turf in a variety of applications, including home lawns, golf courses, athletic fields, parks, pasture and along roadsides. Two types of fescue grasses are most commonly grown: tall fescues and fine fescues. Tall fescue grasses (such as F. arundinacea) have excellent drought and wear resistance. Tall fescue is adapted to a wide range of climactic conditions and is the most predominant cool-season, perennial grass in the United States. (See Tall Fescue, Edited by Buckner and Bush, Published by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. ASA Monograph Number 20. 1979. ISBN 0-89118-057-5). The term fine fescue encompasses several sub-types including hard fescue grasses (F. longifolia); these grasses are low maintenance and shade tolerant, but lack the durability of tall fescue grasses.
Glyphosate (N-(phosphonomethyl) glycine) is the active ingredient in glyphosate herbicides, such as ROUNDUP® herbicide produced by Monsanto, St. Louis, Mo., Credit® herbicide produced by Nufarm, Inc. (Australia), and Razor® herbicide produced by Nufarm Turf and Specialty (Burr Ridge, Ill.). Typically, glyphosate is formulated as a water-soluble salt such as an ammonium, alkylamine, alkali metal or trimethylsulfonium salt. One of the most common formulations is the isopropylamine salt of glyphosate, which is the form employed in ROUNDUP® herbicide.
Glyphosate is a broad spectrum herbicide that inhibits the enzyme enolpyruvylshikimate-phosphate synthase (ESPS). It is conventionally applied as an aqueous solution to the foliage of plants, where it is taken up into the leaves and transported throughout the plant. Commercial formulations of glyphosate may also include one or more surfactants to facilitate penetration of the active ingredient into the plant leaves, as well as compounds to enhance rainfastness. Numerous U.S. patents disclose various formulations of glyphosate, including U.S. Pat. Nos. 4,405,531; 5,118,338; 5,196,044; 5,639,711; 5,652,197; 5,679,621; and 5,750,468.
Therefore, it is desirable to identify plants, such as grass turfs, that are naturally tolerant to glyphosate herbicides. Such tolerant plants can be planted in areas treated with glyphosate herbicides.